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Shifting from aqueous to water lean solvents has been evaluated as a mean for increasing the mass transfer rates in regular chemical solvents with amines. An array of amines (monoethanolamine, 2-methylpiperazine and N-methyl diethanolamine) and diluents (sulfolane, ethylene glycol, 1-methylimidazole, dimethyl sulfoxide, N-methyl-2-pyrrolidinone) has been analyzed.Addition of organic diluents seem to generally induce both a shift in chemical equilibrium and an increase in mass transfer rates for a fixed CO2 partial pressure, though not necessarily for a fixed CO2 loading. However, these relative advantages in terms of mass transfer rates decrease the more loaded the water lean solvent is. The equilibrium shift caused by organic diluents has been evaluated in terms of de-stabilization of the species in the solvent, which for monoethanolamine-based solvents can be easily related to a decrease in dielectric permittivity. However, this analysis indicates that such treatment is insufficient for other types of water-lean solvents, suggesting that different kinds of intermolecular interactions should also be considered in future studies.

Experimental measurements and modelling of the density and viscosity of binary solutions of imidazole, 2-methylimidazole, 2,4,5-trimethylimidazole and 1,2,4,5-tetramethylimidazole with water have been conducted. Parameterization of viscosity data was conducted using a NRTL-model, with AARD of 1% for imidazole, 0.8% for 2-methylimidazole, 3% for 2,4,5-trimethylimidazole and 5% for 1,2,4,5tetramethylimidazole. The density correlations represent the experimental data for imidazole solutions with AARD of 0.1% for all four imidazoles. Viscosities of aqueous imidazole solutions were found to 2 increase upon charging solutions with CO2. Vapor-liquid equilibrium (P, T, x, y) in the range from 313 to 373 K for the aqueous solutions were performed using ebulliometer. The results show that the tested imidazoles exhibit low vapor pressures in aqueous solutions. Finally, it was found there is an insignificant dependence of water activity on temperature within the range of the present study.

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Knowledge on the solubility of gases, especially carbon dioxide (CO 2 ), in monoethylene glycol (MEG) is relevant for a number of industrial applications such as separation processes and gas hydrate prevention. In this study, the solubility of CO 2 in MEG was measured experimentally at temperatures of 333.15, 353.15, and 373.15 K. Experimental data were used to validate Monte Carlo (MC) simulations. Continuous fractional component MC simulations in the osmotic ensemble were performed to compute the solubility of CO 2 in MEG at the same temperatures and at pressures up to 10 bar. MC simulations were also used to study the solubility of methane (CH 4 ), hydrogen sulfide (H 2 S), and nitrogen (N 2 ) in MEG at 373.15 K. Solubilities from experiments and simulations are in good agreement at low pressures, but deviations were observed at high pressures. Henry coefficients were also computed using MC simulations and compared to experimental values. The order of solubilities of the gases in MEG at 373.15 K was computed as H 2 S > CO 2 > CH 4 > N 2 . Force field modifications may be required to improve the prediction of solubilities of gases in MEG at high pressures and low temperatures.

Nonaqueous and aqueous mixtures of methyldiethanolamine and monoethylene glycol form promising absorbents for the combined hydrogen sulfide removal and hydrate control, necessary in natural gas processing. In this direction, the density and viscosity of the binary and ternary systems were measured and modeled in the temperature range of T = 283.15−353.15 K and at ambient pressure. Excess molar volumes and viscosity deviations from ideality were also calculated. The water content varied from 5 to 50 wt % and the amine content from 5 to 90 wt %. Both density and viscosity were modeled using nonrandom two-liquid-based models. Regarding the density modeling, the average absolute relative deviations (AARDs) were found to be less than 0.4% for the binary subsystems and equal to 0.3% for the ternary system. Viscosity modeling results show higher AARD, though always lower than 3.0% for both binary and ternary solutions.